The objective of our research is to determine the integral membrane components involved in the transmembrane control of cell substratum adhesion. Preliminary work in this laboratory has shown that control baby hamster kidney (BHK21/C13) fibroblasts will round up and detach from the substrata when treated with a broad-spectrum antiserum to purified BHK surface membranes. Purification of molecules involved in these responses has resulted in the isolation of a highly restricted population of integral membrane glycoproteins of Mr = 120 to 160 kilodaltons which can block the effects of the antibody. Experiments with murine mammary epithelial cells result in the isolation of a similar class of adhesion-related glycoproteins. A monoclonal antibody recently given to us, which detaches chick myoblasts and perturbs the morphology of chick fibroblasts, also recognizes a family of glycoproteins of 120 to 160 kilodaltons in chick embryo fibroblasts. Thus, this class of glycoproteins appears to be highly conserved. Localization studies suggest that the determinant recognized by the monoclonal antibody is concentrated in both ruffles and the tail region of motile fibroblasts and in the vicinity of adhesion plaques as determined by simultaneous localization with vinculin. Future experiments will: (1)\continue production of monospecific antisera in goats and monoclonal antibodies in mice to components in the 120 to 160 kilodalton glycoprotein fraction from fibroblasts; (2)\determine the effect of these antibodies on the behavior of living cells; (3)\localize the antigens on the surface of adherent and suspension cells in culture and in vivo; and (4)\determine the behavior of these surface antigens with respect to fibronectin and cytoskeletal components following experimental manipulation of the substrata, cell surface, or cytoskeleton. Once specific antibodies for integral membrane components have been obtained, it will be possible to use these probes to purify large quantities of their respective antigens for structural and functional studies and, in the future, to begin to investigate the control of expression of these antigens in normal cells and in cells whose adhesive properties have been altered by mutation or by malignant transformation. (A)